[Karim H et al., 3(11): November, 2016]
ISSN 2349-4506
Impact Factor: 2.785
Global Journal of Engineering Science and Research Management
TENSILE STRENGTH FOR MIXTURE CONTENT RECLAIMED ASPHALT
PAVEMENT
Karim H. Ibrahim Al Helo*, Zaynab I .Qasim, Ahmed D .Majeed
* Assist Professor, Building and Construction Engineering Department, University of Technology,
Baghdad, Iraq
Lecture Doctor, Building and Construction Engineering Department, University of Technology,
Baghdad, Iraq
M.Sc. in Transportation Engineering, Building and Construction Engineering Department, University
of Technology, Baghdad, Iraq
DOI: 10.5281/zenodo.165987
KEYWORDS: Asphalt, Asphalt pavement, Reclaimed Asphalt pavement, Tensile strength, Base course, Base
course content RAP, Recycling.
ABSTRACT
This paper is studying the effect of two different heating temperature of RAP on performance of water sensitivity
tests, the Indirect Tensile Strength Ratio (TSR). the best gradation and optimum asphalt content was Selected
according to Superpave method. Superpave Gyratory Compactor (SGC) used to compact mixture with 100-mm
diameter. Four different percentages (20,30,40 and 50) of RAP used for preparation mixes to compared with virgin
mixture. The test results indicated that addition RAP to mixes shows significant increase on resistance of moisture
damage (TSR) for 110 c‫ ﹾ‬for all percent. For 140 c‫ ﹾ‬showed (TSR) increase to threshold (20%) of RAP while
(TSR) decline for another percent but still above the standard limit of 80%.
INTRODUCTION
The use of Reclaimed Asphalt Pavement (RAP) in different road applications become more widespread in last
two decades. Using RAP has proven to be economical and environmentally sound. The materials present in old
asphalt pavements have residual value even when the pavements have reached to ends of their service lives for
that many agencies and contractors in different countries have made extensive use of RAP in producing new
asphalt pavements to recognize the value of existing aggregate and asphalt (Arshad and Qiu 2013). Researchs
has focused on the effect of RAP addition to bituminous mixes on the variability of volumetric and mechanical
properties of recycled mixtures also the effect of RAP on pavement mechanical behavior. Some of these researches
conclusion, mixtures with similar features as conventional ones were obtained using RAP contents between 10%
and 30% (Alex K. et al. 2011). High RAP contents as 60% have also been prepared but its behavior depending
mainly on the previous RAP homogenization and characterization treatments (Rodrigo Miró et al. 2011).
Performance of pavements with properly prepared recycled asphalt in terms of fatigue, rutting, thermal resistance
and durability proved to be satisfactory (Al-Qadi et al. 2007). Colbert and You (2012) showed that the addition
of 15%, 35%, and 50% of RAP decreased rutting by 24%, and increased resilient modulus by 52%. Study also
showed an increase in dynamic modulus and a decrease in resilient modulus as the RAP percentage increase.
Incorporating high percentage of RAP indicate more rutting resistant mixtures. A.Tabakovic et al. (2006)
indicated that addition (10%,20%,30%) of RAP decrease water sensitivity tests, the Indirect Tensile Strength
Ratio (TSR) but was above the standard limit of 80%, also conclusion the fatigue (ITFT), Circular Wheel Track
(CWT) and Dynamic strain test (DAQ) have slightly improvement in mix performance with the inclusion of 30%
RAP into the mix. Rodrigo Miró et al. (2011) Four mixtures of RAP 0%, 15%, 30% and 50%, was used with
low penetration virgin bitumen. Evaluated moisture sensitivity (TSR) values was dropped with increasing RAP
content but values were higher than 80%. Resistance to rutting, levels of all RAP mixtures being very similar and
lower than that of the high modulus mixture without RAP (rut depth decreased by 30% for 50% RAP and 4.75%
asphalt content). Fatigue behavior was also very much for all mixes, especially with RAP percentages up to 30%,
with dynamic modulus values increasing with increasing RAP content, whereas the stiffness modulus and density
of plant mixes (without RAP preheating) tend to decline.
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[Karim H et al., 3(11): November, 2016]
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Global Journal of Engineering Science and Research Management
MATERIALS USED
Asphalt cement
The grade of binder had used (AC 40-50) or PG (64-16), was obtained from the Dora Refinery, south-west of
Baghdad. The testing was conformed to Iraqi specification (SCRB,2003) and ASTM Requirement. The physical
properties of binder are showing in table (1).
Table 1. Properties of Asphalt Cement
Property
Penetration, (25°C, 100 g, 5s), 0.1 mm
ASTM designation
D-5
Test results
47.3
SCRB specification
40-50
Softening Point. (◦C)
D-36
51.5
……
Ductility at 25 C, 5cm/min, (cm)
D-113
>100
>100
Specific Gravity
Rotational Viscometer, at 135ºC (Pa.sec)
D-70
D-4402
1.03
0.52
……
.….
Rotational Viscometer, at 60ºC (Pa.sec)
D-4402
0.13
Aggregate
The crushed quartz aggregate used in this work was gotten from Al-Sadour quarry; this aggregate widely used in
local asphalt paving in Baghdad. The physical properties of used aggregate were showed in Table (2)
Table 2. Physical properties of aggregate
ASTM designation
Test results
SCRB
Specification
Apparent specific gravity
C-127
2.66
…
Bulk specific gravity
C-127
2.61
…
Water absorption, %
C-127
0.66
…
Percent wear by (Los Angeles abrasion), %
C-131
14.6
35-45 Max
Soundness loss by sodium sulfate solution, %
C-88
3.12
10-20 Max
96%
95 Min
Laboratory Test
Coarse aggregate
Fractured pieces, %
Fine aggregate
Apparent specific gravity
C-128
2.66
…
Bulk specific gravity
C-128
2.62
…
Water absorption, %
C-128
0.68
…
Mineral Filler
The filler used in this work was Portland cement brought from Al-Mas company which provided from local
market. The physical properties of Portland cement are presented in Tables (3).
Tables 3. physical properties of Portland cement
Property
Specific Gravity
Test Result
3.2
%Passing Sieve No.200 (0.075 mm)
100
Reclaimed Asphalt pavement
The reclaimed asphalt pavement materials (RAP) was brought from stoke of Reclaimed Asphalt for Mayoralty of
Baghdad-project office at Altalbia-region in Baghdad city. Extraction test was conducted on the reclaimed asphalt
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[Karim H et al., 3(11): November, 2016]
ISSN 2349-4506
Impact Factor: 2.785
Global Journal of Engineering Science and Research Management
pavement to extraction the asphalt from aggregate and filler. The testing procedure according to (ASTM-D2172).
The percent of asphalt cement was (4%) and gradation of aggregate shown in table (4) the according to (Iraq
specifications’ R9).
Table 4. showed sieve analysis for RAP after extraction
Standard Sieves (mm)
% Passing by weight (R9)
%Passing by weight (RAP)
19
100
100
12.5
90-100
99
9.5
76-90
97
4.75
44-74
73
2.36
28-58
54
0.3
0.075
21-5
4-10
30
4.4
MIX DESIGN
Superppave pavement design method was used to Select Design aggregate structure and Design Asphalt Binder
Content for getting optimum asphalt pavement. Selected aggregate gradation was according to FHWA and Iraq
specifications’ (R9) for base course. Figure (1) shown the gradation of blend selection. after that Four Asphalt
Binder Content was selected (3.45%,3.95%,4.45%,4.95%). The design asphalt binder content is established at
4.0% air voids the design asphalt binder content was 4.42% All other mixture properties were checked at the
design asphalt binder content to verify that they meet Iraq specifications’ (R9) for base course and FHWA. Table
(5) shown design Mixture Properties at 4.42% Binder Content.
Passing %
100
90
80
70
60
50
40
30
20
10
0
0.1
1
Sieve size powered to 0.45
Restricted zone upper
Aggragate Blend selection
10
Restriced Zone down
Upper control points
Fig.1. gradation of blend selection
Table 5. Design Mixture Properties at 4.42% Binder Content
Mix Property
Result
Criteria
%V A
4
4.00%
%VMA Est.
14.5
12 % min
VFA Est.
72.3
65% - 75%
Dust
1.16
0.6 - 1.3
% Gmm @ 𝑁𝑖𝑛𝑖
87.3
less than 89%
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Impact Factor: 2.785
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METHODOLOGY
Recycled hot mix asphalt mixture is a multiphase system, which consists of sized recycled asphalt material, new
asphalt, and/or recycling agents and new aggregates Shaopeng Wu, et al. (2007). Heating RAP should be kept to
a minimum to avoid changing the RAP binder properties. Randy West et.al. (2013). Considering mixing
temperature, recycled aggregates are preheated at a temperature ranging from 110 to 140 ◦C, which is much lower
than the conventional preheated temperatures of fresh aggregates and asphalt binders. The result of rheological
properties of asphalt binders which contain recycled and fresh asphalt binders showed advantages with the
optimization control of recycled hot mix asphalt mixture Shaopeng Wu, et al. (2007). Generally, when the
temperature is higher, the mix workability would be better, since the viscosity of the binder decreases as the
temperature increases (Gudimettla et al., 2003). Based on an experiment (Randy West et.al. (2013)) showed
that Heating stiff RAP for less than 4 hours at 150°C did not significantly change the RAP binder stiffness, while
heating soft RAP at either 110°C or 150°C for more than 2 hours significantly increased the RAP binder stiffness.
Gudimettla JM, et al (2003) recommended that heating RAP temperature at 110°C (230°F) for a time of no more
than 2 h is recommended for sample sizes of 1 to 2 kg. while the virgin aggregate should be heated to 10°C above
the mixing temperature prior to mixing with the RAP and virgin binder. Then the mix components should be
mixed, aged, and compacted as usual and McDaniel, R., and R. M. Anderson (2001) recommended Heat the
RAP for no more than 2 hours in a separate oven set to 110°C (230°F) and the new aggregates should be heated
from 10 to 20 °C above the mixing temperature before combining with the RAP and new binder. Research carried
out by McDaniel et al. (2000) indicated that the properties of RAP binders showed no significant difference
between preheat temperature of 110 and 150 ◦C within 2 h. Exercise care when preparing laboratory specimens
with RAP to avoid changing the properties of the RAP binder, Higher temperatures and longer heating times have
been shown to change the properties of some RAPs McDaniel, R., and R. M. Anderson (2001).
Based on above discussed the Reclaimed asphalt pavement was Heated at 110 C‫ﹾ‬and 140 C‫ﹾ‬for (1-2)

hour. And new aggregate was heating at (170 C‫ﹾ‬
), asphalt pavement (PG 64-16), at (160 C‫ﹾ‬
). After heating
the aggregate and asphalt mixed together and then added heating reclaimed asphalt pavement to mixture.
The percent of reclaimed asphalt pavement (RAP) was added (20%,30%,40%,50%) from total weight
EVALUATION OF MOISTURE SSENSITIVITY
Because of the loss of bond, or stripping, caused by the presence of moisture between the asphalt and aggregate
is a problem in some areas and can be severe in some cases, it is requiring to evaluate the design asphalt mixture
to moisture susceptibility. Many factors such as aggregate characteristics, asphalt characteristics, environment,
traffic, construction practices and drainage can contribute to stripping. This step is accomplished by performing
ASTM D4867 “Effect of Moisture on Asphalt Concrete Paving Mixtures”. Specimens are compacted to (6-8)
% air voids. One subset of three specimens is considered control specimens. The other subset of three specimens
is the conditioned subset. The conditioned subset is subjected to vacuum saturation followed by an optional freeze
cycle, followed by a 24-hour thaw cycle at 60° C. All specimens are tested to determine their indirect tensile
strengths. After conditioning both subsets are tested for indirect tensile strength which is accomplished by Indirect
Tensile Machine in condition of equal speed (50.8mm/min) and the maximum load is recorded.
The moisture sensitivity is determined as a ratio of the tensile strengths of the conditioned subset divided by the
tensile strengths of the control subset. Indirect Tensile Stress is calculated as follows:
𝟐∗𝑷
St =( )… (1)
𝝅𝒕𝑫
where: St = tensile strength, kPa
P = maximum load, N
t = specimen height immediately before tensile test, mm (in)
D = specimen diameter, mm (in.).
Then the Tensile Strength Ratio is calculated as follows:
𝑺𝒕𝒎
TSR = (
)*100 … (2)
𝑺𝒕𝒅
where: TSR= tensile strength ratio, percent
Stm = average tensile strength of the moisture conditioned subset, kPa
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Impact Factor: 2.785
Global Journal of Engineering Science and Research Management
Std =average tensile strength of the dry subset, kPa.
RESULTS AND DISCUSSION
Indirect Tensile Strength Test for Unconditioned Samples
Fig .2. Illustrates the result for (Mix A, Mix B) compared with original mix (0 %, RAP) for unconditioned samples.
The results show indirect tensile strength increase with increase RAP until 40% and the decrease slightly at 50%
of RAP but the value still above the value of original mix. For Mix B indicates that slightly decline for 20% RAP
for TSR value compared with the original mix.
Fig. 2 Indirect tensile strength for unconditioned for Mix A, Mix B
Fig.3.Shows the compared between Mix A and Mix B. The indirect tensile strength for Mix B shows values higher
than Mix A for (30%,40%,50%) but slightly lower for 20% of RAP.
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[Karim H et al., 3(11): November, 2016]
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Impact Factor: 2.785
Global Journal of Engineering Science and Research Management
Indirect Tensile Strength, kPa
1400
1200
1000
800
600
400
200
0
20
30
RAP, %
MIX A
40
50
MIX B
Fig. 3 Indirect tensile strength for unconditioned samples
Indirect Tensile Strength Test for Conditioned Samples
Fig.4. Illustrates the result for (Mix A, Mix B) compared with original mix (0 %, RAP) for conditioned samples.
the results show that the indirect tensile strength increases with an increase in RAP content to threshold (40%)
and then decline at (50%) for both mix.
Fig.4. Indirect tensile strength for conditioned for Mix A, Mix B
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[Karim H et al., 3(11): November, 2016]
ISSN 2349-4506
Impact Factor: 2.785
Global Journal of Engineering Science and Research Management
Fig. 5. Shows the compared between Mix A and Mix B. The indirect tensile strength for Mix A shows values for
20% RAP slightly same that in Mix B and closely value for 50% of RAP.
Indirect Tensile Strength, kPa
1200
1000
800
600
400
200
0
20
30
40
50
RAP, %
Mix A
Mix B
Fig.5. Indirect tensile strength for conditioned samples
Tensile Strength ratio
Fig. 6. shows the tensile strength ratio (TSR) for the both mixes A and B compared with the original mix. Results
show that TSR for Mix A (RAP Heating to110 C‫ﹾ‬
) increases with increase RAP content until 40% RAP content
and the decrease after that for (50%, RAP) but the values still above value that have 20% RAP. For Mix B (RAP
Heating to140 C‫ﹾ‬
) shows that the optimum the value for 20% RAP content and then decline with increase RAP.
The value of 40% RAP content still above the original mix.
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Fig.6. Indirect tensile strength for ratio for Mix A and Mix B
Fig.7. Illustrates tensile strength ratio (TSR) the result for (Mix A, Mix B). The optimum value for Mix A is (40%)
of RAP and then downward but the optimum value For Mix B is (20%) of RAP.
Tensile Strength Reatined, %
1
0.95
0.9
Series1
0.85
Series2
0.8
0.75
20
30
40
50
RAP, %
Fig.7. Indirect tensile strength for ratio
CONCLUSIONS
Based on laboratory test for control original mix prepared with different reclaimed asphalt mix percentages the
following conclusions can be drawn.
1- Indirect tensile strength for reclaimed asphalt pavement heating with 110‫ﹾ‬C for condition samples and
unconditioned samples increase with increase RAP. The optimum value was 40% and the decline but
still over the original mix value.
2- The optimum value of Indirect tensile strength ratio for RAP heating with 110‫ﹾ‬C samples was 40% and
then decline but still above the standard limit of 80%.
3- Indirect tensile strength for reclaimed asphalt pavement heating with 140‫ﹾ‬C for condition samples and
unconditioned samples increase with increase RAP. The optimum value was 40% and the decline but
still over the original mix value.
4- The optimum value of Indirect tensile strength ratio for RAP heating with 140‫ﹾ‬C
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[Karim H et al., 3(11): November, 2016]
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Impact Factor: 2.785
Global Journal of Engineering Science and Research Management
samples were 20% and then decline but still above the standard limit of 80%
REFERENCES
Arshad Hussaina and Qiu Yanjuna (2013),“Effect of Reclaimed Asphalt Pavement on the Properties of
Asphalt Binders” ,Southwest Jiao Tong University (SWJTU), Chengdu, P. R. China.
2. Alex K and et. Al (2010), “Rutting Resistance of Asphalt Concrete Mixtures That Contain Recycled
Asphalt Pavement” Transportation Research Record: Journal of the Transportation Research Board, No.
2208, Transportation Research Board of the National Academies, Washington,
3. Rodrigo Miró and et. Al (2011), “Evaluation of high modulus mixture behavior with high reclaimed
asphalt
pavement
(RAP)
percentages
for
sustainable
road
construction”,
http://www.sciencedirect.com/science/article/pii/S0950061811001462
4. Al-Qadi IL, Elseifi M and Carpenter SH (2007), Reclaimed Asphalt Pavement- A Literature Review,
5. Colbert,B., You,Z. (2012) ,“The determination of mechanical performance of laboratory produced hot
mix asphalt mixtures using controlled RAP and virgin aggregate size fractions”, Journal of Construction
and Building Materials, Vol. 26, 2012,655-662.
6. Amir Tabaković and et. Al (2010), “Influence of Recycled Asphalt Pavement on Fatigue Performance
of Asphalt Concrete Base Courses” http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29MT.19435533.0000093
7. American Society of Testing and Materials (ASTM). (2004) Annual Book of ASTM Standards, Volume
04.03 Road and Paving Materials, Vehicle-Pavement
8. Research Report Fhwa-Ict-07-001, Illinois Center for Transportation.
9. Shaopeng Wu, et al. Investigation of temperature characteristics of recycled hot mix asphalt mixtures
Volume 51, Issue 3, Pages 511-710 (2007).
10. Randy West et.al. (2013) Improved Mix Design, Evaluation, and Materials Management Practices for
Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content, NCHRP Report 752, Final Report.
11. McDaniel, R., and R. M. Anderson (2001), Recommended Use of Reclaimed Asphalt Pavement in the
Superpave Mix Design Method: Technician's Manual NCHRP Report 452
12. Advanced Asphalt Technologies, LLC Sterling, VA (2011): Manual for Design of Hot Mix Asphalt with
Commentary, NCHRP Report 673.
1.
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